Adjustable Frequency Buck or Buck-Boost Pre-Regulator with a

Synchronous Buck, 3 Internal LDOs, Watchdog Timer, NPOR, and FF0/FF1

A4408

7

Allegro MicroSystems, LLC

115 Northeast Cutoff

Worcester, Massachusetts 01615-0036 U.S.A.

1.508.853.5000; www.allegromicro.com

Characteristic

Symbol

Test Conditions

Min.

Typ.

Max.

Unit

GENERAL SPECIFICATIONS

Operating Input Voltage

2.8

13.5

36

V

5.7

13.5

36

V

VIN UVLO START Voltage

5.1

5.4

5.7

V

VIN UVLO STOP Voltage

2.53

2.64

2.78

V

VIN UVLO Hysteresis

–

2.7

–

V

–

13

–

mA

–

–

10

µA

PWM SWITCHING FREQUENCY AND DITHERING

Oscillator Frequency

1.8

2.0

2.2

MHz

–

1.0

–

MHz

343

400

457

kHz

PWM Switching Frequency

Foldback Thresholds

18.7

19.5

20.3

V

–

18.5

–

V

–

7.5

–

V

6.7

7.0

7.4

V

Frequency Dithering

–

±12

–

%

Dither/Slew Start Threshold

8.5

9.0

9.5

V

Dither/Slew Stop Threshold

7.8

8.3

8.8

V

VIN Dithering/Slew Hysteresis

–

700

–

mV

CHARGE PUMP (VCP)

Output Voltage

4.1

6.6

–

V

3.6

4.4

–

V

Switching Frequency

–

65

–

kHz

VCC PIN VOLTAGE

Output Voltage

–

4.65

–

V

THERMAL PROTECTION

155

170

185

°C

–

20

–

°C

1

For input and output current specifications, negative current is defined as coming out of the node or pin (sourcing), positive current is defined as going into the node or pin

(sinking).

2

3

Ensured by design and characterization, not production tested.

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